Model train wheel trip for hot box detectors and the like



Oct. 4, 1966 s. N. HOWELL 3,277,294

MODEL TRAIN WHEEL TRIP FOR HOT BOX DETECTORS AND THE LIKE Filed May 5, 1962 2 Sheets-Sheet l pnmFHn/n VII IF! BISTABLE 2 2 MULTIVIBRATOR m n 1 L20 u uuzuuuuuuu l ff INVENTOR SABERT N. HOWELL To I6 I M ATTORNEYS.

Oct. 4, 1966 s. N. HOWELL w 3,277,294

MODEL TRAIN WHEEL TRIP FOR HOT BOX DETECTORS AND THE LIKE Filed May 5, 1962 2 Sheets-Sheet 2 FIG. 6.

P 5 P F FIG. 7.

INVENTOR SABERT N. HOWELL ATTORNEYS,

United States Patent 3,277,294 MODEL TRAIN WHEEL TRIP FOR HOT BOX DETECTORS AND THE LIKE Sabert N. Howell, Huntington, N.Y., assignor to Servo Corporation of America, Hicksville, N.Y., a corporation of New York Filed May 3, 1962, Ser. No. 192,265 4 Claims. (Cl. 246249) This invention relates to a model train having a novel wheel trip actuating means.

Wheel trips mounted for response to the passing of a car wheel of a train produce signals which are utilized to actuate many types of equipment. One form of a wheel trip which operates as a result of the passing of a conventional wheel of a normal sized car is shown in patent application Serial No. 670,220 filed by Gallagher et al. on July 5, 1957, now abandoned, to which reference may be made. Wheel trips as described in that application find particular utility in actuating gating circuitry in hot box detecting systems, and reference may be made to Patent Nos. Re. 24,983 and 2,963,575 to illustrate such systems.

My invention is intended to simulate a response of gate actuating means or wheel trip means used in conventional hot box detector systems. In this manner, a model train may be used in conjunction with components of a standard size hot box detector system to demonstrate the principles of such system.

Conventional wheel trips as well as a wheel trip such as described in the above Gallagher application are not practical for use with model trains although such wheel trips might be reduced in size. This is particularly true when the model trains have plastic wheels. Further, a model electric train uses a motor in which transient electrical currents as well as D.-C. currents pass through the tracks and could falsely actuate a current sensitive wheel trip. v

An object of my invention is to provide a model train and tracks having novel magnetic wheel trip actuating means associated therewith, which may produce suitable signals to control the actuation of components of a hot box detector system. 1

A further object of my invention is to provide a toy train and tracks having novel magnetic wheel trip actuating means associated therewith to produce suitable control signals.

Another object of my invention is to provide a toy train and tracks having novel magnetic wheel trip actuating means associated therewith to produce suitable control signals without'being falsely actuated by signals produced by the driving motor for the toy train. I

Still another object of my invention is to provide a model train and tracks having novel magnetic wheel trip actuating means associated therewith, which may produce suitable signals to control the actuation of components of a hot box detector system as well as actuating other signaling equipment.

Briefly, I provide a wheel trip which utilizes a conventional magnetic tape head as a pick-up element. The tape head does not have any substantial residual magnetization and operates on the principle that the magnetic reluctance of the core element is varied in accordance with the amount of magnetic material passing adjacent to an air gap provided therein. Magnetic elements are carried by the model train so as to pass adjacent to the air gap to vary the reluctance of the magnetic circuit. All of the magnetic elements must present a common pole face to the tape head. However, the magnetic elements do not touch the tape head magnetically so as to transfer their magnetization thereto.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing, wherein:

FIGURE 1 is a plan view of the model railroad track showing two pick-ups of my invention mounted between the rails;

FIGURE 2 is alongitudinal sectional view along 22 of FIGURE 1 also showing the wheels of a model train car and the relative position of the magnetic actuating elements;

FIGURE 3 is an underside perspective view of the wheel mounting on a model train showing the mounting of the magnetic actuating elements;

FIGURE 4 is an underside plan view of the wheel assembly of FIGURE 3 in the direction of 44 of FIGURE 3;

FIGURE 5 is a diagrammatic showing of the magnetic actuating element moving over the surface of the pick-up;

FIGURE 6 represents the waveforms produced at various locations of the system;

FIGURE 7 is a comparison of certain waveforms.

Referring now to the drawings, there is shown in FIG- URE 1 a railroad track 10 comprising model rails 11 and 12 spaced apart in conventional fashion and mounted upon transversely extending ties 13. A first magnetic responsive means or magnetic wheel trip means 14 is located between the ties which may be cut as illustrated for this purpose. A second magnetic responsive means 15 is secured adjacent to the first one along the direction of the track. Each of these magnetic responsive means contains a sensitive area 14' and 15', respectively, which, as will be seen hereafter, constitutes an air gap which controls the reluctance of the magnetic responsive means. The air gaps are spaced apart a predetermined distance along the direction of the track. The magnetic responsive means is mounted slightly higher than the height of the ties so that the sentitive areas are just above the rail head.

The output from the first magnetic means is applied over wire 16 to an A.-C. amplifier 17 which output turns on bistable multivibrator 20. The output from magnetic means 15 is applied over lead 18 to an A.-C. amplifier 19 to turn off the multivibrator 20.

The system described is primarily useful in the operation of conventional hot box detector systems which work on the principle of space gating. Space gating allows the infrared detector to lookat a passing journal box for a predetermined distance regardless of the speed of the train. Other hot box detecting systems have been utilized in which a wheel trip is actuated in response to a passing wheel so as to allow an infrared detecting element to scan a journal box for a predetermined time. The output from such a wheel trip may be applied to a monostable multivibrator which would have a predetermined time of operation. The system which uses a monostable multivi'brat-or allowing an infrared sensor to scanthe passing journal box for a predetermined time is said to utilize time gatingl When a space gating system is utilized, the magnetic responsive means 14 and may be spaced a predetermined distance apart such that the sensitive areas 14' and '15 are a predetermined distance D apart as shown in FIGURE 2. The actuating magnetic element comprises a magnet 21 in the form of a bent magnetized wire mounted so as to present a pole of a predetermined polarity (which may for purposes herein be a north pole) to the sensitive area. The end of the north pole is positioned in line with the bottom of the wheel which comes in contact with the rail so that it is actuated substantially at the same time that the wheel contacts the space of the rail which is parallel to the sensitive area 14. That is, the head of the magnet 21 is placed on a point which is substantially in line with a vertical line which passes through the center of the wheel and is also positioned slightly above the height of the ties (such as, for example, by of an inch).

Since there is associated one journal box for each wheel, a second magnetic element 22 which also presents a north pole to the sensitive area is provided. Therefore, both magnets present a common pole to a sensitive area.

FIGURE 3 is a perspective view looking upwards into the wheel assembly shown in FIGURE 2. The wheel assembly comprises four wheels which are held in fixed spaced apart relationship by axles 25 and 26 and axle frames 27 and 28. A supporting member positioned between axles 2-5 and 26 carries a magnetic insulative block 29 which may, for example, be formed of aluminum which supports the other ends (the south poles) of the magnetized wires '21 and 22. These ends of the magnetized wires are therefore held in spaced magnetically insulative relationship. A screw 30 is provided to remove the insulative block 29 when necessary. If desired, the supporting member has suitable formations to receive the ends of the magnetized wire which may be held in place or clamped in place by the non-magnetic element 29.

The wire 21 has a right angle bend and has a forward end 2 1' which is parallel to the axle 25. End 21' connects to a longitudinally extending part 22 which extends downwardly at an angle to horizontal from the insulative block 29 to such a distance that the front part 21' may pass closely adjacent to the top of the magnetic responsive means 114. As shown in FIGURE 5, the magnetic responsive means comprises a conventional tape head formed of a circular core 61 of low magnetic reluctance having an air gap 32 defined therein. The air gap 32 is the sensitive area and is positioned at the top of the magnetic responsive means so that passing magnetic elements may alter the reluctance of the air gap and hence, the reluctance of the entire magnetic core element, to produce an electrical signal in a wrap-around coil 33. One end of coil 33 may be grounded while the other end connects to Wire I116.

Conventional tape heads do not have any appreciable residual magnetization. However, the magnetic elements 21 and 22 are true magnets and have relatively high residual magnetism. Therefore, in order to prevent the transfer of this magnetism to the core 31, a thin plastic layer 34 or any other magnetic insulative layer is positioned across the top surface of the magnetic responsive means so as to securely insulate any of the pole heads of the magnetic wires 21 and 22 from the core 31. In practice, it is desirable that the headof the magnet be spaced somewhat :from the top surface of 34 such as, for example, approximately one-thousandth of an inch. Since the air gap 32 must be the sensitive region, the plastic layer 34 only served to prevent the magnetic elements 21 and 22 from touching the magnetic means. Hence the train carried permanent magnets 21 and 22 not only vary the reluctance of the air gap, but, in this embodiment, induce a voltage in the coil element.

The operation of the system may be explained by referring to FIGURES 6 and 7. The passage of the magnetic element 21 over the magnetic means "14 produces a first signal S as shown in FIGURE 6a. This signal is very small and is actually of somewhat irregular shape varying somewhat between a square wave and the sinusoidal wave. Since the signal is of the level .001 volt, amplification is required. However, because of the high level of background signals produced by the electric motor of the train, the gain of the amplifier cannot be so high as to amplify the background signals. When an A.-C. amplifier is used, there is necessarily a certain amount of differentiation so that the output from the amplifier as shown, for example, by amplifiers '17 and 19 may be of the character of the signal S as shown in FIG- The signal S shown in FIGURE 60 is actually the output from an A.-C. amplifier while the signal S in FIG- URE 6b is intended to represent an intermediate shape in which differentiation occurs; Because of the capacitive coupling which exists in A.-C. amplifiers a certain amount of differentiation will occur. The bistable multivibrator 20 may be conventional having a certain threshold level, as is indicated diagrammatically in FIGURE 60. The shade-d area of the signal S of FIGURE 60 is used to initiate the start of the pulse from the bistable multivibrator. This pulse is shown by the letter P on FIG- URE 6d and the letters Ps and Pf are intended to represent the start of the pulse and the finish of the pulse.

When the magnetic element 21 passes over the sensitive region 15', a signal S shown in FIGURE 6a is produced. This signal is produced a predetermined time T after the first signal which time will vary in accordance with the speed of the train. The differentiated signal S is shown in FIGURE 6b and the output from amplifier 19 is shown at S in FIGURE 60. Again, when the signal S rises above the threshold level, the bistable multivibrator is turned off.

The operation of the magnetic element 22 is similar. When it passes over sensitive area 14', a signal 8;; is produced as shown in FIGURE 6a which signal is operated upon to produce the signal S shown in FIGURE 6a and when it passes over sensitive area 15, a series of signals S are produced.

In one aspect of the invention, it is essential that each of the magnets 21 and 22 present a common polarity to the magnetic mean-s 14. If the presenting pole of the magnet 22 was a south pole or if the magnets 21 and 22 were combined to form a single magnet, then the operation of the system when utilizing bistable multivibrator for the space gating purposes described would not be efiective. This may be seen by referring to FIGURE 7. A first pole of magnetic element 21 would produce the signals S as described originally. However, when the next element which would be a south pole positioned as shown in magnet 22 passes over the sensitive region 14', an inverse pulse signal shown in FIGURE 7 would be produced. Differentiation would produce a pulse as illustrated in FIGURE 7b and as shown the output signal would not be above the threshold level. Under such circumstances, it is evident that the second pulse would not turn off the bistable multivibrator.

The bistable multivibrator is part of the standard hot box detecting system. Other gating means (relays) may be used in place of the bistable multivibrator. In order to start the bistable multivibrator (or such other gating means) the output signals from amplifiers 17 and 19 preferably should be widened. This is necessary since the signals S -S (shown in FIGURE 60) may be of such short duration that gating means, particularly when relays are used, will not trip reliably. In this case, two monostable multivibrators may be added in circuit with the amplifiers 17 and 19. In the embodiment shown in FIGURE 1, the monostable multivibrators will be added in series between the outputs of amplifier 17 and the gating means and between the inputs of amplifier 19 and the gating means.

A.-C. amplifiers are preferred to D.-C. amplifiers because the signals to be amplified are pulses and are at a very low voltage level wherein the stability of the D.-C. amplifier would present a problem.

While the foregoing description sets forth the principles of the invention in connection with specific apparatus, it is to be understood that this description is made only by way of example and not as a limitation of thescope of the invention as set forth in the objects there-. of and in the accompanying claims.

6 I claim: termined relationship with said wheels to be sub- 1. A model train and wheel trip assembly for space stantially in line with the tangential contacting arc gating comprising of the wheel which is in contact with the rail,

two magnetic means having air gaps therein, said second magnetic element having its first end supsaid air gaps being positioned longitudinally one behind 5 ported in said magnetic insulative material and the other in the direction of the movement of the said second extending end being positioned in pretrain, determined relationship with the tangential arc of said air gaps being positioned at a distance corresaid second wheel,

sponding to the desired space of the gating, said extending ends having the same polarity. a model train carrying first and second magnetic pole 1O T C mbinati n of Claim 3 in which said magl m t netic elements are bent wires, a part of said wires being o e of id magnetic l t b i positioned i secured transverse to the direction of movement of said determined relationship with a wheel, trainsaid second magnetic pole element being positioned in predetermined relationship with a wheel behind said References Cited by the Examiner first e UNITED STATES PATENTS eaerlliorof tsjlud tmagne-tic pole elements having a com- 470,923 3/1892 Edison the end: o f s aid magnetic element com risin said 1334520 3/1920 Chittenden at 246 193 polarities being ositioned at a distance to a ctuate 2850249 9/1958 Uderstadt 104-88 X said magnetic mea ris successively 2877718 3/1959 Mitt-ag 246249 X 2 The combination of claim 1 in which the other ends 2981830 4/1961 Davls et 246*249 X of said magnetic elements are secured in magnetic in- 3O16456 1/1962 Corporon 104 88 X 3,030,499 4/1962 Pagenhardt 246-249 X sulative relat1onsh1p.

3. A model train and wheel trip assembly comprising Eagles ]0488 X two from Wheels ossart et a 10488 X two wheels spaced to the rear of said front wheels, FOREIGN PATENTS maglrnletilc insulative means positioned between said 132,232 3/1933 Austria.

w ee s, first and second magnetic elements, ARTHUR L. LA POINT, Primary Examiner.

a first end of said first magnetic element being positioned and held by said magnetically insulative ma- LEO QUACKENBUSH Examine terial, S. B. GREEN, Alisistant Examiner.

the second extending end being positioned in prede- 

1. A MODEL TRAIN AND WHEEL TRIP ASSEMBLY FOR SPACE GATING COMPRISING TWO MAGNETIC MEANS HAVING AIR GAPS THEREIN, SAID AIR GAPS BEING POSITIONED LONGITUDINALLY ONE BEHIND THE OTHER IN THE DIRECTION OF THE MOVEMENT OF THE TRAIN, SAID AIR GAPS BEING POSITIONED AT A DISTANCE CORRESPONDING TO THE DESIRED SPACE TO THE GATING, A MODEL TRAIN CARRYING FIRST AND SECOND MAGNETIC POLE ELEMENTS, ONE OF SAID MAGNETIC ELEMENTS BEING POSITIONED IN PREDETERMINED RELATIONSHIP WITH A WHEEL, 